http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png
Untersuchungen zur SEC-unabhängigen Membrantranslokation der Glukose-Fruktose Oxidoreduktase aus Zymomonas mobilis



1999
Forschungszentrum, Zentralbibliothek Jülich

Jülich : Forschungszentrum, Zentralbibliothek, Berichte des Forschungszentrums Jülich 3661, 111 S. () = Zugl.: Düsseldorf, Univ., Diss., 1999

Please use a persistent id in citations:

Report No.: Juel-3661

Abstract: The periplasmic NADP-containing glucose-fructose oxidoreductase (GFOR) of the gramnegative bacterium Zymomonas mobilis belongs to a class of redox cofactor-dependent enzymes which are exported with the aid of a signal peptide containing a so-called twinarginine motif. The replacement of one or both arginine residues results in drastically reduced translocation of GFOR to the periplasm, showing that this motif is essential. Mutant proteins which, in contrast to wild-type GFOR, bind NADP in a looser and dissociable manner were severely affected in the kinetics of plasma membrane translocation. These results strongly suggest that the translocation of GFOR into the periplasm uses a Sec-independent apparatus which recognizes, as additional signal, a conformational change in the structure of the protein, most likely triggered by cofactor binding. Furthermore these results suggest that GFOR is exported in a folded form. A GFOR::~-galactosidase fusion protein is not lethal to Z. mobilis cells and leads to the accumulation of cytosolic preform of wild-type GFOR expressed in trans but not of a typical Sec-substrate (OmpA), indicating that the GFOR translocation apparatus can be blocked without interfering with the export of essential proteins via the Secpathway. In higher plant chloroplasts, twin-arginine signal peptides are specific targeting signals for the Sec-independent ilpH-pathway of the thylakoid membrane system. In agreement with the assumed phylogenetic origin of this protein transport mechanism, GFOR can be efficiently translocated by the ilpH-dependent pathway when analyzed with isolated thylakoid membranes. Transport is sensitive to the ionophore nigericin and competes with specific substrates for the Aplf-dependent transport route. In contrast, neither sodium azide nor enzymatic destruction of the nucleoside triphosphates in the assays affects thylakoid transport of GFOR indicating that the Sec-apparatus is not involved in this process. Mutagenesis of the twin-arginine motif in the GFOR signal peptide prevents membrane translocation of the protein emphasizing the importance of these residues for the transport process

Keyword(s): membrane transport ; biological membrane ; bacterium ; protein secretion ; bioengineering ; reductase


Note: Record converted from JUWEL: 18.07.2013
Note: Zugl.: Düsseldorf, Univ., Diss., 1999

Contributing Institute(s):
  1. Institut für Biotechnologie (IBT)

Database coverage:
OpenAccess
Click to display QR Code for this record

The record appears in these collections:
Document types > Reports > Reports
Workflow collections > Public records
Publications database
Open Access

 Record created 2013-07-18, last modified 2020-06-10


OpenAccess:
Download fulltext PDF
External link:
Download fulltextFulltext by OpenAccess repository
Rate this document:

Rate this document:
1
2
3
 
(Not yet reviewed)